An injection molding machine includes a cylinder into which molding material (for example, resin pellets) are fed, a screw that is rotatably and advanceably/retractably provided inside the cylinder, a plasticizing motor that rotates the screw, and an injection motor that advances the screw. The plasticizing motor rotates the screw and forwardly delivers a molding material fed into a spiral-like groove of the screw. The cylinder has multiple band heaters provided to its outer periphery. The heat of the multiple band heaters is transferred to the cylinder and gradually melts the molding material advancing into the cylinder. As the molten molding material is delivered to the front of the screw and accumulates at a front part of the cylinder, the screw is retracted. Then, the injection motor advances the screw, so that the molten material delivered to the front of the screw is ejected from a nozzle provided at the front part of the cylinder and fills a cavity space inside a mold unit.